Ginkgo leaf extracts have been shown to have a wide range of biological activities. The most well-known use among American is the perceived ability of the products to improve short term memory. Other important effects include a protective effect on the blood-brain barrier and an anti-radical (antioxidant) effect. The leaf extracts has also been shown to increase vasodilation and peripheral blood flow rate in capillary vessels and end-arteries in various circulatory disorders. Ginkgo leaf helps to maintain integrity and permeability of cell walls by inhibiting lipid peroxidation of membranes. Other studies have shown vascular-tone regulating effects, and help in modulating cerebral energy metabolism.